Wednesday, December 28, 2016

Living so close to the Snake River means I see more fog than many others in the Treasure Valley. The image below was taken several days ago after our largest snow storm this season. It shows the setting sun peeking over the top of a fog bank over the Snake River. The sky is very dark because molecules in the atmosphere doesn't scatter sunlight as well as it does blue light and it's shorter wavelength.

I have three images to share from a quadcopter flight over my snowy house. The altitude each picture was taken was only around 200 feet. By the way, all three pictures have roughly the same orientation.

The first picture was taken with a color camera. So it's of the house in visible light.

The second was taken in near-infrared. This image looks like it was taken at a higher altitude because of the camera's wider field of view.

The last one is in thermal infrared, which shows sources of heat. You can identify me as the warm spot on the left side of the house and in front of the garage.

Friday, December 23, 2016

Have you ever wondered how well sound is transmitted through near space? How about how different audio frequencies behave in near space?

NearSys announces a new flight computer called the BalloonSat Sound of Near Space. It creates tones and illuminates LEDs so that inexpensive digital camcorders can record sounds for analysis in software like Audacity.

Tuesday, December 20, 2016

The new NearSys flight computer has one primary mission, recording light intensity in eight spectral bands. The bands are defined by the eight LEDs included in the kit. The LEDs span the range from near ultraviolet to infrared.

LEDs work as villagers because not only emit specific colors, they also emit current when exposed to the color of light that they emit.

Here's an example of the data that the BalloonSat Photometer collects. The lag between the 940 nm and 890 nm spectral data indicates the presence of water vapor in the cloud that blocked light between 10:50 and 11:30 AM.

The BalloonSat Photometer measures and records eight spectral bands and operates two cameras. With 128 kbits of memory, it will record light intensity data all day.

Learn more about the BalloonSat Photometer at, http://nearsys.com/arhab/flightdata/2016/g/index.htm

Monday, December 12, 2016

NearSys just released a new BalloonSat Flight Computer, five new sensor kits, and updated two old sensor arrays.

New BalloonSat Flight Computer
The new flight computer is called the BalloonSat Mini Servo. In place of one sensor, there's a servo. This lets a BalloonSat physically manipulate an experiment, like opening and closing a Petri dish during a mission. You can select from three sensors for this flight computer, temperature, pressure, or relative humidity. See, BalloonSat Mini Servo for complete information.

New Near Space Sensors
The new sensor designed for the BalloonSat Mini is a temperature and pressure sensor which you can see at, Temperature and Pressure Sensor.

Sunday, December 11, 2016

Nope, there's no error in the title; data is plural for datum. Here are ten examples of data collected during a typical near space mission. Each is easily captured using a programmable flight computer.

Temperature is something everyone understands. Best of all, it's easily measured with a LM335 temperature sensor connected to a microcontroller with analog-to-digital capability. The LM335 is a temperature-controlled Zener diode that produces a voltage proportional to its temperature. The voltage increases by 100 mV for every 100 kelvin increase in temperature. Theoretically, it produces zero volts at absolute zero and 5.00 volts at 500 kelvins (441 degrees F). Most people are aware that air temperature decreases with increasing altitude (in fact, at a rate of 1 degree F for every 300 foot increase in altitude in the Troposphere). What many people are not aware of is that the air temperature begins increasing again with altitude once one enters the Stratosphere. In fact, the switch in the lapse rate is what delineates the Stratosphere for the Troposphere. The air temperature of the Troposphere decreases with increasing altitude because the ground warms the lowest layer of the atmosphere. As you move away from this source of heat, the air temperature decreases. The air temperature in the Stratosphere increases with increasing altitude because solar ultraviolet and ozone warms the upper layers of the atmosphere. As you approach this source of heat, the air temperature increases.

Everyone is aware of the fact that air pressure decreases with increasing altitude. And anyone who has brought a sealed bag of potato chips to a mountain excursion has seen the sealed bag expand and becomes stiffer as he or she drives higher. Earth's gravity pulling down on the gas molecules making up the atmosphere creates air pressure. Gravity makes the air pile up on the ground creating more air pressure at the surface and less the higher one goes. As a balloon climbs higher, it experiences a decrease in air pressure the higher it climbs. The rate at which the air pressure decreases with altitude is a function of three factors, the average mass of the molecules making up the atmosphere, the air temperature, and the acceleration due to gravity. A convenient description for the rate of an atmosphere's decrease in air pressure is called the atmosphere's Scale Height (H). By definition, Scale Height is the change in altitude needed to decrease the air pressure by a factor e, or 2.718... In the case of Earth, the Scale Height is 8.5 km, 5.2 miles, or 27,375 feet. Another way to look at the lapse rate or Earth's atmospheric pressure is that it decreases by half for every 18,000 foot change in altitude.

Relative Humidity is a comparison between the amount of water vapor dissolved in the atmosphere (absolute humidity in units of grams water per kilogram of atmosphere) and the amount of water vapor the atmosphere can hold in solution at its current temperature and pressure. In other words, relative humidity is a measure of the atmosphere's level of saturation. The atmosphere can hold less and less water vapor at higher and higher altitudes. This is because the atmosphere's density decreases with increasing altitude. The relative humidity however tends to remain constant with altitude except when near sources of water. The Earth's surface is one large source of water in the form of lakes, streams, and moist ground. At altitude, the relative humidity spikes near clouds. Above the clouds however, there are no large reservoirs of water for the atmosphere to draw upon and therefore the relative humidity tends to be low. Water vapor absorbs infrared light and this is one reason infrared observatories are built on tall mountain tops.

Cosmic Rays are not actually rays. Rays are electromagnetic radiation and they consist of photons, or particles of light. Photons have no mass; they travel at the speed of light and are the subatomic particle responsible for carrying the electromagnetic force between charged objects. Eighty-five percent of Cosmic Rays consist of protons and 12% of alpha particles, or helium nuclei. A small percentage of detected cosmic rays are mesons, but those are the product of the collisions between cosmic rays and molecules of gas in the atmosphere. Very rarely, gamma rays (a form of electromagnetic radiation) are found in Cosmic Rays. The source of Cosmic Rays appears to be supernovae explosions. The strong magnetic fields associated with the explosion of massive stars are capable to accelerating some of the supernova atoms to high energies. The Cosmic Rays then travel within the galaxy until they strike Earth's atmosphere. Physicists refer to them as primary Cosmic Rays as they enter the atmosphere. A collision between a primary Cosmic Ray and a molecule of nitrogen or oxygen in the atmosphere creates a shower of subatomic particles called secondary Cosmic Rays. The secondary Cosmic Ray can create addition showers of subatomic particles that are lower in energy than the original particle. Eventually, most Cosmic Rays are absorbed by the atmosphere as they gain electrons and turn into ordinary molecules.

Physicists divide Ultraviolet radiation into three broad ranges, UV-A (315 nm - 400 nm), UV-B (280 nm - 315 nm), and UV-C (100 nm - 280 nm). UV-C is used as a germicidal, in other words it destroys cells and is therefore very dangerous to humans. Fortunately, it's entirely blocked high in the atmosphere by the ozone layer inside the stratosphere. The majority of UV-B is blocked in the ozone layer, but some does reach the surface and gives tans and sunburns. UV-A is the band of ultraviolet most likely to reach the surface and it too gives people sun tans and sun burn. UV-B is more dangerous than UV-A because of the large amount of energy packed inside of its photons. However, even UV-A is dangerous in excess amounts. The UV-B Flux chart from data recorded on this near space mission shows an increase in the flux once the balloon has climbed above 30,000 feet. At this point, the balloon has entered the ozone layer and so there's less ozone to block UV-B from the sun. But this isn't the only reason it's increasing. The sun's increasing elevation above the horizon is a second factor for creating an increase in UV-B flux. As the sun climbs higher, its light travels through less air and therefore less ozone. Finally, the jaggedness of the data is due to spinning and swinging of the BalloonSat carrying this sensor. Sometimes the data was collected when the sensor faces more directly towards the sun and at other times when the sensor was pointed more away from the sun.

Viewing the ground below with a thermal imager shows surface temperature variations across a large swath of land. A person could collect the same data by carrying a thermometer across 100 square miles of land. In this image, yellow and white represent the warmest locations and blue and black the coldest. The Owyhee Mountains are a desert mountain range. It's dry grasses warm quickly at sunrise and therefore appear yellow in this image. The neighboring farmlands are well-irrigated, leafy green, and therefore cooler. The red streak visible in the mountains is a valley receiving some sheltering from the rising sun. A balloon took this image at an altitude of 94,400 feet.

Even better is to record images of the ground in visible light and thermal infrared at the same time. This image taken at 13,000 feet shows the Snake River and two of its many islands. The river's water is warmer than the surface temperature of the islands and their foliage. The neighboring farmland is cooler than the open desert next to it and a lot cooler than the Snake River. There's a structure, perhaps a barn on the edge of the farm that shows up as the white spot in the visible image. It's apparently much cooler this morning because it appears as a small blue spot in the thermal image.

A thermal imager shows just how cold clouds can be. This image taken at 42,000 feet includes clouds that appear black to the thermal imager. Clouds are water vapor condensed into water droplets. They occur where the temperature of the atmosphere is at the dew point. Unless there's fog on the ground, the dew point is colder than the surface air temperature. Since the air temperature decreases with increasing altitude, we can expect clouds to be colder than the ground.

Near infrared is the portion of the electromagnetic spectrum bordering between the infrared and visible red. The atmosphere is very good at scattering blue light from the sun through a process called Rayleigh Scattering. It occurs because molecules of oxygen and nitrogen are roughly the size of a blue photon's wavelength. In the case of red or even infrared light, the wavelength is too long for the smaller molecules comprising the atmosphere to affect them very strongly. Unless there is a lot of atmosphere, as there is when looking at the horizon, very little red or infrared light is scattered by Rayleigh Scattering. This picture of the horizon was taken at an altitude of 38,000 feet. The distance to the horizon is 250 miles, yet this image shows mountains nearly all the way to the horizon in crisp detail. The sky is black because no infrared has been scattered out of the sunlight, except very close to the horizon.

A picture taken in infrared from an altitude of 72,000 feet shows details of the ground otherwise invisible in visible light. If this was a regular color picture, the ground would have a bluish cast to it and that blue haze would blur out some of the details. Since it is infrared, we see sharp relief in the Owyhee Mountains (left side), some of the erosion of the mountains towards the Snake River Valley, the Snake River and several of its many islands, and Lake Lowell. Farmland still with crops appears white. That's because chlorophyll is reflective to red and infrared light. Near infrared images is a good way to estimate the health of plants since healthy plants are rich in chlorophyll.

Wednesday, December 7, 2016

Near Space is a region of Earth’s atmosphere above 60,000
feet (or the top of controlled air space) and below 328,000 feet (or the
boundary of outer space). Most aircraft cannot fly within near space, and those
that are capable of flying here are military-related and can only reach
altitudes of 100,000 feet. Weather balloons can reach the lower half near space
and because they are relatively cheap, they allowed amateur scientists like me
to turn near space into an exciting destination for exploration. GPS receivers,
amateur radio, and programmable microcontrollers are the three basic components
necessary for any near space mission. Tracking and therefore recovering a near
spacecraft is possible because of the combination of GPS receivers and amateur
radio, but it is programmable microcontrollers that allow amateurs to operate
sensors, including cameras, within this substitute for outer space. Here are
ten images recorded by near spacecraft during their missions of amateur
exploration.

A near spacecraft is a stack of modules. The stack can
easily be 30 feet tall and consists of (from the top to the bottom) a
hydrogen-filled or helium-filled weather balloon, load line (connects the
balloon to a parachute and prevents the burst balloon from collapsing on top of
the parachute), a recovery parachute, one or more tracking modules, and
experiments built into airframes called BalloonSats (balloon satellites). The
balloon topping the near spacecraft is capable of lifting upwards of 15 pounds
of payload and is around six feet in diameter at launch. It expands in size as the
near spacecraft ascents until it reaches its maximum diameter of 20 to 25 feet.
The balloon’s burst frequently occurs at an altitude between 85,000 and 100,000
feet. With a climb rate of 1,000 feet per minute, most near space ascents
require 90 minutes to complete. Within a second or two after the burst, the
parachute is open and the near spacecraft is descending at speeds in excess of
70 miles per hour. Denser air close to the ground slows the parachute until the
near spacecraft lands at a gentle speed of ten miles per hour. With smart
planning and a pinch of luck, the chase and recovery crew is present to watch
the landing.

There are two popular methods to launch a near spacecraft.
One of them we call a Hail Mary launch. It’s the preferred launching method when
surface winds make it unsafe to raise each near spacecraft modules individually.
During a Hail Mary launch, the near spacecraft remains horizontal with the launch
crew supporting each module above and away from their heads. The balloon is located
upwind of the near spacecraft’s modules. That way, at release the balloon climbs
up and drifts over each module of the near spacecraft. One by one, each module
lifts out of the supporting hands of the crew member holding it. But watch out!
The variable nature of the wind and the long length of the near spacecraft means
it’s possible for a module to lift out of your hand with a side ways motion. It’s
important that crew members to wear hard hats, especially the one supporting
the final module of the near spacecraft.

We usually program the microcontroller onboard the near
spacecraft to collect data and record images at fixed intervals of time, like
every 30 seconds. So it’s possible for a near spacecraft to record an image
just prior to or just after launch. This near spacecraft recorded an image just
a few seconds after launch. Visible in the image are three of the launch crew
watching the near spacecraft they just released. Below the camera taking this
image is a back-up tracking module. A GPS receiver and amateur radio are packed
inside of a reusable lunch sack. Many of the commercially available electronics
we use to explore near space do not like the -60 degree Fahrenheit temperatures
found between the troposphere and stratosphere. This means that a reusable
lunch sack makes an ideal airframe for the tracking electronics since the lunch
bag includes insulation and padding. Besides, a beeping lunch sack with an
antenna sticking out of it looks perfectly harmless when it lands in your front
yard.

The distance across this low-altitude image is five miles,
meaning it would take you at least five minutes to drive across it. We can see
a low cliff cuts diagonally across the leftmost third of this image and a small
creek is visible twisting its way across the lower right corner. Some of the farm
sections are dark green, indicating crops here have grown thick. In other
sections, the ground below the crops is clearly visible. This indicates that the
crops there have not had enough time to grow in. Four student-designed
BalloonSats are also visible in this image. The students responsible for them
were part of a summer aeronautical camp where they learned the importance of
aeronautics to the state of Idaho.
The BalloonSat activity was a closure activity and in it, they collected images
and temperatures from near space. If the students had more time, they could
have used images like this to make maps and determine land use.

Clouds consist of tiny water droplets held aloft by a
combination of their drag and rising air currents. As the near spacecraft climbs
through a cloud, the sun illuminates the top and bottom of the cloud making it
easy to see the ragged fluffs near the base and crown of the cloud. However, once
inside a cloud, the camera only sees a grey-colored haze similar to what people
see when they stand inside a fog bank. These near space images illustrate that
fog is merely a cloud on the ground. A relative humidity sensor will show relative
humidity levels approaching one hundred percent as the near spacecraft
approaches clouds. Therefore, an onboard GPS receiver in conjunction with a
relative humidity sensor is one way to determine the altitude of clouds. A
temperature sensor will indicate if the cloud consists or liquid or solid
water. This data along with imaging shows that clouds exist at a variety of altitudes
and different shapes and compositions.

This image is over 13 miles long from front to back. The
flat surface of water in this Kansas
reservoir reflects sunlight near the middle of the image like a mirror. This
indicates that the wind speed is so low at the surface that the water is smooth
and not choppy. The near spacecraft is still low enough to make out individual
buildings, since it was launched only a few minutes earlier. The buildings and
parking lots are interspersed with trees and roads. The roads, we can see stop
at or work their way around the reservoir. The atmosphere is deeper closer to
the top of the image making the air’s haziness more apparent as you look
through more atmosphere. The image is of LakeShawnee, east of Topeka. The river at the top is the
meandering Kansas River. Two islands and a
sand bar are visible in the river. The roads on the left edge of the image are
the I-470/I-70 interchange. Images taken at an angle, rather than straight down
are less useful for mapping but more interesting from an artistic point of
view.

The higher the near spacecraft climbs, the bluer the ground below
the near spacecraft becomes. Why? It’s because more of the atmosphere is located
below the near spacecraft and no longer above. The atmosphere primarily consists
of molecules of oxygen and nitrogen that nearly the same size as a wavelength
of blue light. One result of this match in size is that molecules in the
atmosphere scatter blue wavelengths of light more strongly than they scatter red
wavelengths of light. On the ground, no matter which direction you look in the
sky, you are seeing blue light emitted by the sun. In near space, the same is only
true when you look down. This mission took place over eastern Kansas where the land is divided into one
mile squares bordered by gravel county roads. Each square mile encompasses four
sections, each one half mile on a side. The small community below is next to an
airport. From the scale of this image, we can determine that the runway at this
airport is 7,000 feet long.

Near space missions launched 75 minutes before local sunrise
experience a sunrise scene similar to the one astronauts see from their perch
in Earth orbit. In near space, the sun rises up to 20 minutes earlier than on
the ground below because at that height, the near spacecraft can see well over
the edge of Earth. In fact, in near space the horizon can appear as much as
five degrees lower than it does from the ground. So the 180 degrees of sky we
see on the ground becomes 190 degrees in near space. The lack of air in near
space also means that the sky overhead never turns red with the approach of
dawn. All the atmospheric play of color we enjoy on the surface is compressed
into a narrow band of electric color rimming Earth’s eastern horizon.
Silhouettes of clouds make the edge of Earth appear rough against the coming
dawn. When visible, the Morning Star, Venus is visible as a pin point of light
in images like this.

We’re accustomed to seeing the sky turn blue with the advent
of sunrise. This is never the situation in near space, especially once the near
spacecraft ascends above 85,000 feet. Rather, the sky overhead remains pitch black
and the sun becomes an intense disk of light. The sun’s light is richer in blue
and ultraviolet because the lack of air can no longer scatter it out. The
digital camera taking this picture was unable to render an image of the sun due
to its intensity – this is not an image of a total solar eclipse from near
space. Below the near spacecraft, a contrail from a jet airplane remains long
after the airplane has left the scene. Contrails are the result of water from
the jet’s exhaust condensing on the particulate matter emitted by jet engines. The
fact that the contrail appears this long indicates that the air at the jet’s altitude
is humid. The drier the air, the more quickly the water and ice droplets
evaporate back into the air and the shorter the contrail.

Images like these are why I
got hooked on amateur near space exploration. For an astronaut wannabe like me,
images from near space are the closest I’ll come to traveling into space - the
near spacecraft is my space avatar. Twice now, photo lab technicians have asked
if I was an astronaut when I asked them to print photographs like this. In images
like these, the curvature of Earth’s horizon and the blackness of space becomes
apparent. Earth is definitely a planet set in the inky blackness of airless
space. There are no political boundaries visible from near space; even through
the horizon is 400 or more miles away. In this image, a thunderhead rises above
lower stratus clouds. For launch crews, the sky was an amorphous mass of gray
and it wasn’t until after recovery that they realized storm clouds were
overhead. Amateur near space exploration is open to everyone. If you want
pictures taken from a very different perspective, web search for your closest
near space group or consider getting an amateur radio license and starting your
program.